This invention relates generally to improvements in radio frequency identification (RFID) devices or tags, and related reader systems and processes for communicating therewith. More particularly, this invention relates to an improved, semi-active RFID tag adapted for association with a specific individual or object, as by mounting onto or within a wristband or the like, wherein the RFID tag incorporates an on-board thin, flexible, printable battery compatible with enhanced signal transmission range and relatively rapid signal transmission speed, and further wherein the tag includes a power management system for conserving battery power and thereby prolonging battery service life. The power management system is designed for activating the tag battery on an as-needed basis, and for minimizing battery power drain by enabling limited portions of the tag circuitry as required for a specific communication protocol and its operation predetermined by “super commands”.
Radio frequency identification (RFID) devices or tags are generally well known in the art, wherein a relatively compact electronic device or circuit is mounted onto or otherwise incorporated within a convenient structure such as an identification card or wristband or the like adapted for mounting onto a specific individual or object. The RFID tag is designed for receiving and storing identification and other information associated with the person or object attached thereto, and a compatible reader is provided for radio frequency communication with the RFID tag for positively identifying the person or tracking the person or object, etc. Such identification bands have been widely used or proposed for use, e.g., for patient identification in a medical facility or the like, for personnel identification and/or access control at secured facilities such as military or industrial installations and the like, for patron identification at amusement parks and events such as concerts and the like, for airport passenger and/or baggage identification, for identification and tracking shipped parcels, and for animal control, and the like. When used for patient identification in a medical facility, the RFID tag may further receive and store important additional information such as patient medical condition and/or treatment regimen. For illustrative examples of identification bands and the like including RFID technology, see U.S. Pat. Nos. 5,493,805; 5,973,598; 5,973,600; 6,181,287; and 6,414,543, and copending U.S. Publications US 2003/0173408 and US 2003/0174049, which are incorporated by reference herein.
In the past, RFID devices or tags have generally been designed for receiving power from the ambient field radiating from a reader. That is, the RFID tag has not been provided with an on-board battery for powering the RFID circuitry. Instead, the RFID circuitry has been externally powered by a magnetic field produced by the reader in the course of communicating with the RFID tag. In such so-called “passive” RFID tags, communication is inherently and necessarily initiated only by the reader, and such communication has been limited to relatively short-range signal transmission and relatively slow data transmission speeds. By way of example, in a typical RFID tag powered by a magnetic field (H-field) radiating from a reader, present power restrictions imposed by the Federal Communications Commission (FCC) dictate a relatively short-range communication on the order about one meter or less. For alternative passive RFID tags powered by an electric field (E-field), the communication range is longer, i.e., up to about 10 meters. Accordingly, for passive-powered RFID tags, the tag and reader must be in relatively short-range proximity to each other, while the transmission speed effectively limits the amount and type of data to be transferred.
To achieve increased signal transmission range and data transfer speed, so-called “active” RFID devices or tags have been produced with an on-board battery for powering the RFID circuitry. However, battery power drain has imposed a significant limitation on the utility of such active RFID tags. That is, in a compact flexible RFID tag of the type used on a patient wristband on the like, size and other physical restraints on battery design, including but not limited to flexibility requirements in a compact and lightweight wristband design, inherently results in an on-board battery having limited charge storage capacity. In an attempt to increase battery service life in this environment, the RFID tag is normally in a de-activated or “off” state, with circuit activation being initiated by an appropriate signal from a compatible reader. Accordingly, similar to a “passive” tag, communication is again initiated only by the reader. Upon activation, the circuitry incorporated into the “active” RFID tag has been fully enabled or powered up, thereby maximizing battery power drain during data transactions.
There exists, therefore, a significant need for further improvements in and to RFID devices and tags, wherein a compact and lightweight thin and flexible on-board battery is provided for improved signal transmission range and data transmission speed, but further wherein the RFID tag includes a power management system for minimizing battery power drain upon circuit activation. In addition, it is desirable to provide such improved RFID tag which is not limited to reader-initiated communication, but instead may perform a variety of tag-initiated communication protocols and provides full utilization of the surface area of the tag for enhancing communication distance. The present invention fulfills these needs and provides further related advantages.